title: The added value of eye-tracking in diagnosing dyscalculia: a case study.
abstract: The present study compared eye movements and performance of a 9-year-old girl with Developmental Dyscalculia (DD) on a series of number line tasks to those of a group of typically developing (TD) children (n = 10), in order to answer the question whether eye-tracking data from number line estimation tasks can be a useful tool to discriminate between TD children and children with a number processing deficit. Quantitative results indicated that the child with dyscalculia performed worse on all symbolic number line tasks compared to the control group, indicated by a low linear fit (R (2)) and a low accuracy measured by mean percent absolute error. In contrast to the control group, her magnitude representations seemed to be better represented by a logarithmic than a linear fit. Furthermore, qualitative analyses on the data of the child with dyscalculia revealed more unidentifiable fixation patterns in the processing of multi-digit numbers and more dysfunctional estimation strategy use in one third of the estimation trials as opposed to ~10% in the control group. In line with her dyscalculia diagnosis, these results confirm the difficulties with spatially representing and manipulating numerosities on a number line, resulting in inflexible and inadequate estimation or processing strategies. It can be concluded from this case study that eye-tracking data can be used to discern different number processing and estimation strategies in TD children and children with a number processing deficit. Hence, eye-tracking data in combination with number line estimation tasks might be a valuable and promising addition to current diagnostic measures.
authors.affiliation: Department of Cognitive and Motor Disabilities, Utrecht University Utrecht, Netherlands.
authors.forename: Sietske
authors.initials: S
authors.lastname: van Viersen
authors.forename: Esther M
authors.initials: EM
authors.lastname: Slot
authors.forename: Evelyn H
authors.initials: EH
authors.lastname: Kroesbergen
authors.forename: Jaccoline E
authors.initials: JE
authors.lastname: Van't Noordende
authors.forename: Paul P M
authors.initials: PP
authors.lastname: Leseman
keywords: diagnostic procedures; dyscalculia; eye-tracking; mapping; number line; number sense